DETERIORATION OF WATER QUALITY - THE EFFECTS ARISING FROM THE USE 0F
FACTORY APPLIED CEMENT MORTAR LININGS (ESP 9770) FINAL REPORT TO THE
DEPARTMENT OF THE ENVIRONMENT
Report No DWI0255
- To identify and quantify the water quality problems caused by
the use of factory applied, cement mortar lined, iron water
- To provide guidelines on the limitations of application of
factory applied cement mortar linings;
- To recommend methods for overcoming the potential water
quality problems associated with the use of such linings.
In 1986, the Department of the Environment (DoE) commissioned WRc
Plc to investigate the effect that in situ cement mortar lining had
on water quality. These studies(1) showed conclusively that in situ
lining of iron water mains in soft water supply regions can lead to
pH, aluminium and lead levels which contravene the EC Directive(2)
on potable water and the Water Supply (Water Quality) Regulations
The findings of this work led to concern that similar problems may
be associated with factory applied cement mortar linings; the work
reported in this document was commissioned by the Department of the
Environment in April 1989 to investigate this.
A series of laboratory, full scale test-rig and field studies have
been implemented in order to determine the effects of factory
applied cement mortar linings on water quality.
Particular emphasis has been placed on the development of laboratory
test-rigs which provide practical alternatives to costly full scale
test-rig and field studies.
Data has been appraised in relation to previous in situ studies(l),
and recommendations for use of factory linings have been developed.
- Factory applied linings are more satisfactory for use at lower
alkalinities than in situ linings. In the case of 100 mm
diameter pipes, and provided that retention time does not exceed
8 hours at any time, factory linings can be used when the supply
water alkalinity is greater than 25mg CaCO3/l. At lower
alkalinity levels leaching can cause pH levels to exceed the EC MAV
and Water Act 1989 MAV of 9.5.
- When using cement mortar as a corrosion inhibitor for entire or
large parts of distribution systems, the cumulative effect
associated with long total retention times may result in pH in
excess of 9.5 at the consumers tap. Very long retention times
may result in high pH levels, even though the alkalinity is
significantly greater than 25mg CaCO3/l.
- Seal coatings appear to provide an effective method of pH
control; however, their long term durability and the potential
for any water quality problems associated with such coatings
have not been established.
Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.
- Factory applied cement mortar lined pipes should not be used in
conditions of very low alkalinity (less than 25mg CaCO3/l),
where pipe diameters are small and retention times are relatively
long. Caution should be exercised when considering the use of such
linings when the total retention time is very high, even though the
supply water alkalinity may be in excess of 25mg CaCO3/l.
- Theoretical extrapolation of the data should be used to provide
an indication of the potential pH levels in a given defined system.
- The use of approved seal coatings, epoxy linings and other
methods of preventing elevated pH should be considered in future
- Further field data should be collected to substantiate the
findings of this work, which are mainly based on laboratory and